Heterocyclic studies. Part III. Hydrates of ethyl pteridine-4-carboxylate and some methyl derivatives

Abstract

Ethyl pteridine-4-carboxylate, and its 7-methyl- and 6,7-dimethyl-derivatives have been converted into covalently dihydrated species (V)–(VII) in which two molecules of water are added across the 5,6- and 7,8-bonds. Dihydrates of this type have been obtained in pure solid form from the anhydrous pteridines (I)—(III) in two ways and also directly from ethyl 5,6-diaminopyrimidine-4-carboxylate without going through the anhydrous pteridine. In at least one case different stereoisomers of a hydrate have been isolated. The u.v., i.r., ¹H n.m.r., and mass spectroscopic data are recorded.